Boreholes are drilling into earth formations for various purposes such as hydrocarbon production, geothermal production and carbon dioxide sequestration. The boreholes are typically drilled using a drill tubular coupled to a drill bit. In order to make efficient use of the earth formations, they are characterized using downhole tools such as logging tools coupled to the drill tubular. The tools provide formation property measurements while the boreholes are being drilled in operations referred to as logging-while-drilling (LWD) or measurement-while-drilling (MWD).
The downhole tools generally require electrical power to operate. Unfortunately, providing electrical power from the surface while drilling is not practical. Thus, electrical generators disposed in a drill tubular may be used to convert the energy of mud flowing in a drill tubular to electrical power in order to power the downhole tools. Due to the confines of a bottomhole assembly (BHA) housing the tools, the amount of power generated by conventional downhole mud generators may be limited. Hence, it would be well received in the drilling industry if new downhole mud generators would be developed to generate more electrical power than conventional downhole mud generators or adapt to a required amount of electrical power.